Display devices are known comprising at least a pair of electrodes of opposite polarity, one or more of said electrodes being positioned relative to a background which provides a first degree of contrast when the electrodes are electrically inactive and a second degree of contrast when the electrodes are electrically active. Usually, the first degree of contrast is low and the second degree high, but the background may be selected such that its appearance shows less contrast when the electrodes are electrically active than when they are electrically inactive.
Generally the less discernible an electrode is when its degree of contrast is low, the smaller is the likelihood of confusion arising between the display in that degree of contrast and the display in the higher degree of contrast. The discernibility of an electrode is a function of its sharpness of definition and of its degree of contrast with the background. We have now found that if the display device comprises a visible pattern the outline of an electrode may be lost in the pattern so that the electrode may become less discernible at low degree of contrast and hence the likelihood of confusion is diminished.